1) Human growth hormone isohormone B is needed as a starting material for enzymatic digestion leading to bioactivation, and as a bioactivity control. A procedure for isolation of hGH-B (28%) from a mixture with isohormones C, D and E (72%) was elaborated, using isotachophoresis at acid pH. 2) Metallothionein, a Zn and Cd binding peptide from liver and brain, was characterized in a crude homogenate as a single charge isomeric species, existing in 3 size isomeric forms. 3) Glucocorticoid receptor from chick embryonic retina, purified by sucrose density sedimentation, was found to exhibit protein-protein interactions indistinguishable from the crude solubilized receptor.